linux-kernel - Re: [PATCH] mtd: rawnand: omap2: Actually prevent invalid configuration and build error

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Date:   Fri, 4 Mar 2022 12:04:21 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Randy Dunlap <rdunlap@...radead.org>
Cc:     Roger Quadros <rogerq@...nel.org>,
        krzysztof.kozlowski@...onical.com, vigneshr@...com, nm@...com,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: rawnand: omap2: Actually prevent invalid
 configuration and build error

On 3/4/22 07:54, Miquel Raynal wrote:
> Hi Guenter, Roger,
> 
> rdunlap@...radead.org wrote on Sat, 26 Feb 2022 22:55:28 -0800:
> 
>> On 2/19/22 16:44, Guenter Roeck wrote:
>>> On Sat, Feb 19, 2022 at 09:36:00PM +0200, Roger Quadros wrote:
>>>> The root of the problem is that we are selecting symbols that have
>>>> dependencies. This can cause random configurations that can fail.
>>>> The cleanest solution is to avoid using select.
>>>>
>>>> This driver uses interfaces from the OMAP_GPMC driver so we have to
>>>> depend on it instead.
>>>>
>>>> Fixes: 4cd335dae3cf ("mtd: rawnand: omap2: Prevent invalid configuration and build error")
>>>> Signed-off-by: Roger Quadros <rogerq@...nel.org>
>>>
>>> Tested-by: Guenter Roeck <linux@...ck-us.net>
>>
>> Tested-by: Randy Dunlap <rdunlap@...radead.org>
> 
> Sorry for noticing that just now, but there is still a problem with
> this patch: we now always compile-in the OMAP_GPMC driver whenever we
> need the NAND controller, even though it is not needed. This grows the
> kernel for no reason.
> 

Sorry, you lost me.

> In fact, Roger once said:
> 
> 	"We will figure out how to enable OMAP_GPMC for K3 architecture
> 	some other way."
> 
> It turns out this is not what was finally proposed. Could we try yet
> another solution?
> 
>>
>> Thanks.
>>
>>>    
>>>> ---
>>>>   drivers/mtd/nand/raw/Kconfig | 3 +--
>>>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
>>>> index 36e697456ec4..9b078e78f3fa 100644
>>>> --- a/drivers/mtd/nand/raw/Kconfig
>>>> +++ b/drivers/mtd/nand/raw/Kconfig
>>>> @@ -42,8 +42,7 @@ config MTD_NAND_OMAP2
>>>>   	tristate "OMAP2, OMAP3, OMAP4 and Keystone NAND controller"
>>>>   	depends on ARCH_OMAP2PLUS || ARCH_KEYSTONE || ARCH_K3 || COMPILE_TEST
>>>>   	depends on HAS_IOMEM
>>>> -	select MEMORY
>>>> -	select OMAP_GPMC
>>>> +	depends on OMAP_GPMC

No matter if select or depend, both result in OMAP_GPMC enabled
if MTD_NAND_OMAP2={m,y}, and both suggest that OMAP_GPMC is
needed for MTD_NAND_OMAP2. That conflicts with

  we now always compile-in the OMAP_GPMC driver whenever we
  need the NAND controller, even though it is not needed
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

If it isn't needed, why the dependency in the first place ?
Also, commit 4cd335dae3cf2 states "this driver depends on OMAP_GPMC
driver and uses symbols from there". Are you saying that this is not
correct ?

Guenter